This is the first of 12 dispatches I’ll write, one a week through mid-April, that will chronicle the first nationwide do-it-yourself mass protest, and by far the biggest demonstration yet against global warming.

If all goes well — and by “all going well,” I mean “if you help” — then on Saturday, April 14, we’ll kick off the approach to Earth Day with hundreds upon hundreds of simultaneous rallies all across America, designed to start pressuring Congress to take decisive action on climate change.

Americans will gather in iconic places across the country. Some will be familiar at a glance: the top of the Grand Teton, underwater off Hawaii’s coral reefs, on the levees above the Ninth Ward, along a blue line on Canal Street in Manhattan that marks the city’s possible new beachfront. Others will be less famous: the steps of your church, the picnic grove in your city park, the biggest barn in your county. But everywhere people will be saying, loud and clear, that it’s finally time for serious action from Washington, D.C., on the mightiest problem the world has ever faced.

All you need to take part is a crowd — small in small places, bigger in big places — and a digital camera. By nightfall we’ll have a cascade of images for everyone, including local and national media, to look at. We’ll have proof that Americans care deeply enough to act. It should be lovely in every sense of the word.

We’re not an organization. There are seven of us: six recent college graduates earning the sum of $100 a week for their labors, and me, earning only the chance to exorcise some of the ghosts that have been haunting me since I wrote The End of Nature in 1989. For almost two decades, the few of us working on climate change felt like we were trapped in a bad dream, unable to get anyone else to see the monster looming behind them. In the last couple of years, that’s begun to change. Thanks to Hurricane Katrina and Hurricane Gore, public opinion has turned. Polling shows people know there’s a problem, that they want action. And we have the scientists to tell us exactly what’s wrong, the engineers and the economists to offer useful solutions. There have been dozens of good books in the last two years, and fine documentaries. Every Rotary Club in America has seen An Inconvenient Truth.

We have, in other words, all the parts of a movement except the movement itself.

Earlier this year, a few of us led a march across Vermont for global-warming action. By the end of five days and 50 miles, we had a thousand people marching. That was sweet — it was enough to insure that all our state’s candidates for Congress pledged to support 80 percent cuts in carbon emissions by 2050. But it was also sad. Because that thousand people was the largest global-warming demonstration yet held in this country.

We could change that with a march on Washington. But traveling to Washington spews an immense amount of carbon. And anyway, for the first time in history, we have the tools to do this a different way: to assemble in the places that mean the most to us, the very places that will be wrecked as the planet warms, and make our point there. With digital video cameras and YouTube; with cell-phone pictures and Flickr. With the tools to let our political leaders know that people back in their districts care, that this isn’t a second-tier issue — something to deal with far in the future — or with penny-ante compromises.

Anyone can play. Some of the day’s actions are being organized by Sierra Club chapters and NRDC offices; many more will come from local groups who know that the cove or wetland or inner city or community garden that they’ve worked to protect and nourish is threatened by drought and sea level rise. Many more still will be organized by people who aren’t official activists at all, just so concerned about climate change that they’re ready to do something. We’re using that same goal we used in Vermont: 80 percent cuts by 2050. But the numbers are less important than the intent — it’s time to finally start doing something, and something on the same scale as the problem we face.

We have most of the tools you need to make a rally work: banners, pointers on working with reporters, and more. And you have the most important tool: your list of friends and their email addresses. All you’re asking is that they assemble for an hour on a Saturday to hoist a banner and take a picture. And each of them has a list of email addresses, and …

The key first steps are to forward this small essay to as many people as you think might act on it, and then go to our website — StepItUp2007.org — and sign up to host a rally. It’s not a perfect website yet, but it will get better quickly. And already it shows what really matters: a kind of desperate creativity from across the country. Desperate but joyful. And ready to get started.